Add support for switching the audio output device for HTMLMediaElements.

media/base/audio_renderer.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_AUDIO_RENDERER_H_
 #define MEDIA_BASE_AUDIO_RENDERER_H_
 
+#include <string>
+
 #include "base/callback.h"
 #include "base/time/time.h"
 #include "media/base/buffering_state.h"
 #include "media/base/decryptor.h"
 #include "media/base/media_export.h"
 #include "media/base/pipeline_status.h"
+#include "url/gurl.h"
 
 namespace media {
 
 class DemuxerStream;
 class TimeSource;
 
 class MEDIA_EXPORT AudioRenderer {
  public:
   AudioRenderer();
 
@@ skipping 38 matching lines @@
   virtual void Flush(const base::Closure& callback) = 0;
 
   // Starts playback by reading from |stream| and decoding and rendering audio.
   //
   // Only valid to call after a successful Initialize() or Flush().
   virtual void StartPlaying() = 0;
 
   // Sets the output volume.
   virtual void SetVolume(float volume) = 0;
 
+  // Switches the output device.

[miu, 2015/06/03 21:01:01]

Please do the same here as I suggested in AudioRendererSink (re: documentation,
naming the type of the callback, and using an enum).

+  virtual void SwitchOutputDevice(
+      const std::string& device_id,
+      const GURL& security_origin,
+      const base::Callback<void(int)>& callback) = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(AudioRenderer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_RENDERER_H_